Personalized ring-back tones (PRBT) are mobile telecommunication services offered to mobile service subscribers. When a caller dials the number of a PRBT subscriber, the caller may hear a tune, sound, jingle, phrase, advertisement, etc., instead of the traditional switchboard ringtone. With the PRBT service, subscribers have yet another way to express their own individuality.
An early PRBT called Color Ring Back Tone (CRBT) was introduced by a South Korean company, Witcom in May 2001 and started service with SK Telecom in South Korea from April 2002. Since then, numerous companies have supplied PRBT equipment for mobile phone and telecommunications companies. Many mobile operators now offer PRBT services to their customers.
Unfortunately, the subscribers' individual selections of a PRBT are not always agreeable. For example, some of the PRBTs are weird, raspy, shrill, hoarse, offensive, and/or otherwise troublesome. However, in current systems the caller has no choice but to hear the subscribers' PRBT.